added frontend

hartmann-foto-documentation-frontend/lib/utils/extensions.dart

@@ -0,0 +1,29 @@
+import 'package:flutter/material.dart' show Colors, Color;
+
+extension HexColor on Color {
+  /// String is in the format "aabbcc" or "ffaabbcc" with an optional leading "#".
+  static Color fromHex(String hexString) {
+    final buffer = StringBuffer();
+    if (hexString.length == 6 || hexString.length == 7) buffer.write('ff');
+    buffer.write(hexString.replaceFirst('#', ''));
+    return Color(int.parse(buffer.toString(), radix: 16));
+  }
+}
+
+extension RiskColor on Color {
+  static const Color noRisk = Colors.transparent;
+  static final Color lowRisk = HexColor.fromHex("#FFFF00");
+  static final Color mediumRisk = HexColor.fromHex("#FF9000");
+  static final Color highRisk = HexColor.fromHex("#FF4000");
+
+  static Color colorForRisk(int value) {
+    if (value == 1) {
+      return lowRisk;
+    } else if (value == 2) {
+      return mediumRisk;
+    } else if (value == 3) {
+      return highRisk;
+    }
+    return noRisk;
+  }
+}